Sun Java logo     Previous      Contents      Index      Next     

Sun logo
Sun Java System Communications Express 6 2004Q2 Administration Guide  

Chapter 9
Tuning and Performance Information

This chapter describes the information you need to consider for improving the performance of Sun Java System Communications Express.

To improve performance consider the following tuning options

Tuning Directory Server

This section describes the tuning you can perform on Directory Server to enhance performance.

Indexing the LDAP Directory Server

To improve the performance of Communications Express when Calendar Server accesses the LDAP directory server, index the following LDAP attributes:


The script adds indexes for icsCalendar, icsCalendarOwned, mail, and mailAlternateAddress attributes.

Setting the nsSizeLimit and nsLookthroughLimit Parameters

It is important that the nsSizeLimit and nsLookthroughLimit parameters in User/Group LDAP directory server configuration is large enough for searches to be completed properly.

To determine if these parameters are set to appropriate values, type the following command:

ldapsearch -b /base/ (&(icscalendarowned=*/user/*)(objectclass=icsCalendarUser))


/base/ is the LDAP base DN of the directory server where the user and resource data for Calendar Server is located.

/user/ is the value that an end user can enter in Calendar Search dialog under the Subscribe option in Communications Express.

The LDAP server returns an error, if the nsSizeLimit or the nsLookthroughLimit parameter is not large enough.

Follow these guidelines to reset nsSizeLimit or the nsLookthroughLimit parameters:

Tuning Calendar Server

This section describes how load balancing across multiple CPU on Calendar Server can enhance performance.

Using Load Balancing Across Multiple CPU

If a server has multiple CPUs, by default Calendar Server distributes the HTTP Service such as cshttpd processes and Distributed Database Service such as csdwpd processes across CPUs.

The service.http.numprocesses and service.dwp.numprocesses parameters in ics.conf determine the actual number of processes that run for each service. By default, these parameters are set to the number of CPUs for the server during installation, but you can reset these values. For example, if a server has 8 CPUs, but you want a cshttpd and csdwpd process to run in only 4 CPUs, set the parameters as:



    To disable load balancing
  1. Add the service.loadbalancing parameter to the ics.conf file
  2. Set service.loadbalancing to “no.
  3. Restart Calendar Server for the change to take effect.

For information on load balancing refer to the chapter on Calendar Server Performance Tuning in Sun ONE Calendar Server 6.0 Administration Guide at:

Tuning Web Server

This section describes the tuning you can perform on Web Server to enhance performance.

Setting the value of acceptorthreads

In server.xml, change the value of the attribute acceptorthreads present in <vs> (virtual server) element to the number of CPUs on the machine hosting Web Server.

For Example:

<VS id="" connections="ls1" mime="mime1" aclids="acl1" urlhosts="<webserver host name"acceptorthreads="<noofcpus>" >

Setting JVM Options

Set the following JVM options in the server.xml file of Web Server.

The following two parameters determine the Heap size of JVM

It is recommended to have the same parameters for both the options, for example,


Set the following parameters for Garbage Collection

Tuning Communications Express

In the file, enable compression of the sever response by setting the uwc.gzip compression parameter value to “true.” For example, uwc.gzipcompression = true

Then restart the Web Server.


Maintain a backup of your configuration files before making any changes.

Previous      Contents      Index      Next     

Copyright 2004 Sun Microsystems, Inc. All rights reserved.